Due to the rapid increase of petroleum prices and environmental pollution problems caused by waste polymers, there is increased interest in plant-derived polymer materials. Plant-derived polymer materials generally do not impose a heavy environmental burden and can be recycled as they are obtained from biomasses. Of particular interest are biodegradable polymers capable of being naturally decomposed in soil or landfills.
Among biodegradable polymers, aliphatic polyester polymers have been the most studied since the aliphatic polyester polymers have excellent workability and easily controlled decomposition properties. In particular, polylactic acid (PLA) has a 100,000 ton-scale market all over the world, and the uses of the same are expanding to include food containers and packaging materials and fields in which general plastics for electronic appliance cases and the like have been used. Until recently, polylactic acid resins have mainly been used in disposable products, for example, food containers, wraps, films and the like.
However, thin film products formed of existing polylactic acid resins can be easily damaged when they are molded from the existing polylactic acid resins since the existing polylactic acid resins can have insufficient moldability, mechanical strength and heat resistance. In particular, the shape of molded products formed of existing polylactic acid resins can be deformed if exposed to an external temperature of 60° C. or higher since the existing polylactic acid resins have low high temperature resistance.
Recently, research has focused on blending general-purpose resins having high heat resistance and mechanical properties with polylactic acid. Such methods have gained attention since these methods can suppress the consumption of general-purpose resins derived from petroleum raw materials and thus can reduce environmental burdens associated with the same by lowering carbonic acid gas and combustion heat generated when recycling general-purpose resins.